From the field of viewpoint of safety and convenience, vehicles on which an automatic wiper system for detecting the amount of rainfall and automatically controlling an operation of a wiper device is mounted have been on the increase in recent years. Such a wiper system controls the wiper operation according to the amount of rain. As the amount of rainfall increases, the wiper speed is appropriately switched from INT (intermittent activation state) to Lo (low speed activation state: normal activation state) to Hi (high speed activation state) (or continuously in some models of vehicles). However, in the event of a heavy rainfall such as a sudden localized heavy rain, squall, and rain gust, even a system including a raindrop sensor may have difficulty in securing the field of view, since a large amount of rain adheres to the windshield immediately after a wiping operation with the wiper operation switched to the Hi activation. In particular, in a “torrential rain” with more than 50 mm of one-hour rainfall, it has often been the case that the forward field of view is not available and driving operation becomes difficult even in an attempt to pull off the vehicle to an appropriate place for safety.
A configuration such as described in Patent Document 1 has been heretofore proposed as means for coping with a large amount of rainfall like a localized heavy rain. According to Patent Document 1, two types of wipers including a reciprocating swing wiper and a rotary wiper are used as wiper devices. If the amount of rain exceeds the limit of the wiping capability of the reciprocating swing wiper, the reciprocating swing wiper is stopped and the rotary wiper is activated. In such a manner, a torrent of rain is removed from the windshield to increase the transparency and ensure the field of view of the driver even during a heavy rain.